Continental Resources Inc. Chairman Harold Hamm is defending his 2013 meeting with Oklahoma's state seismologist. He says he was simply seeking information from a state agency, not pressuring seismologist Austin Holland to change scientific findings.

When an earthquake rocked Cherokee, Okla., in early February, cracking walls in the Alfalfa County courthouse, regulators told SandRidge Energy Inc. to shut down a disposal well about 5 miles away.

The earthquakes displayed were located in Oklahoma and occurred from Jan. 2, 2008, until Jan. 15, 2015, based on Oklahoma Geological Survey information. The earthquakes are a minimum 2.0 magnitude. Click map to link to animation. Map courtesy of USGS.

About This Report

A surge in seismic activity is occurring around the U.S., and many top scientists are pointing at injection of waste from drilling and hydraulic fracturing as a possible culprit.